The present invention relates to an internal combustion engine and, more particularly, relates to the internal combustion engine in which a variable lift and/or operating angle mechanism which variably controls a lift and/or operating angle of an exhaust valve and a variable phase mechanism which variably controls a phase of a lift center angle of the exhaust valve are equipped.
A Japanese Patent Application First Publication No. 2001-65321 published on Mar. 13, 2001 exemplifies a, previously proposed variably operated valve apparatus for the internal combustion engine. In the previously proposed variably operated valve apparatus, a first variable mechanism which variably controls at least a lift characteristic of an engine valve in accordance with an engine driving condition, a second variable mechanism which variably controls at least an open-and-closure timing characteristic of the engine valve, and position detecting means for detecting a present position of either the first variable mechanism or the second variable mechanism are provided and an operation of one of the first and second variable mechanisms which does not fail is controlled to fall in a predetermined range in accordance with the position of the other of first and second variable mechanisms in accordance with the position of the other of the first and second variable mechanisms which has failed detected by the position detecting means, when one of the first and second variable mechanisms has failed. In the above-described Japanese Patent Application First Publication, when one of the first and second variable mechanisms has failed, the lift characteristic or the phase is controlled so as to avoid interferences between a piston and an associated engine valve and between an intake valve(s) of the engine valve and the exhaust valve(s) thereof. Thus, while avoiding a mechanical trouble, a reduction in mechanical performance is prevented.